Coupled Ferroelectricity and Correlated States in a Twisted Quadrilayer MoS₂ Moire Superlattice

Moire superlattices have emerged as a highly controllable quantum platform for exploration of various fascinating phenomena, such as Mott insulator states, ferroelectric order, unconventional superconductivity and orbital ferromagnetism. Although remarkable progress has been achieved, current research in moire physics has mainly focused on the single species properties, while the coupling between distinct moire quantum phenomena remains elusive. Here we demonstrate, for the first time, the strong coupling between ferroelectricity and correlated states in a twisted quadrilayer MoS2 moire superlattice, where the twist angles are controlled in sequence to be similar to 57 degrees, similar to 0 degrees, and similar to -57 degrees. Correlated insulator states are unambiguously established at moire band filling factors v = 1, 2, 3 of twisted quadrilayer MoS2. Remarkably, ferroelectric order can occur at correlated insulator states and disappears quickly as the moire band filling deviates from the integer fillings, providing smoking gun evidences of the coupling between ferroelectricity and correlated states. Our results demonstrate the coupling between different moire quantum properties and will hold great promise for new moire physics and applications.